于 2013/3/5 10:23, Michael Ellerman 写道:

On Tue, Jan 15, 2013 at 03:38:55PM +0800, Mike Qiu wrote:

quoted

Adding a function irq_create_mapping_many() which can associate
multiple MSIs to a continous irq mapping.

This is needed to enable multiple MSI support for pSeries.

Signed-off-by: Mike Qiu <redacted>
---
  include/linux/irq.h       |    2 +
  include/linux/irqdomain.h |    3 ++
  kernel/irq/irqdomain.c    |   61 +++++++++++++++++++++++++++++++++++++++++++++
  3 files changed, 66 insertions(+), 0 deletions(-)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 60ef45b..e00a7ec 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h

@@ -592,6 +592,8 @@ int __irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node,
  #define irq_alloc_desc_from(from, node)		\
  	irq_alloc_descs(-1, from, 1, node)
  
+#define irq_alloc_desc_n(nevc, node)		\
+	irq_alloc_descs(-1, 0, nevc, node)

This has been superseeded by irq_alloc_descs_from(), which is the right
way to do it.

Yes, but irq_alloc_descs_from() just for 1 irq, and if I change the api, 
maybe a lot places which call this
function will be affact.

quoted

diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index 0d5b17b..831dded 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h

@@ -168,6 +168,9 @@ extern int irq_create_strict_mappings(struct irq_domain *domain,
  				      unsigned int irq_base,
  				      irq_hw_number_t hwirq_base, int count);
  
+extern int irq_create_mapping_many(struct irq_domain *domain,
+					irq_hw_number_t hwirq_base, int count);
+
  static inline int irq_create_identity_mapping(struct irq_domain *host,
  					      irq_hw_number_t hwirq)
  {

diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 96f3a1d..38648e6 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c

@@ -636,6 +636,67 @@ int irq_create_strict_mappings(struct irq_domain *domain, unsigned int irq_base,
  }
  EXPORT_SYMBOL_GPL(irq_create_strict_mappings);
  
+/**
+ * irq_create_mapping_many - Map a range of hw IRQs to a range of virtual IRQs
+ * @domain: domain owning the interrupt range
+ * @hwirq_base: beginning of continuous hardware IRQ range
+ * @count: Number of interrupts to map

For multiple-MSI the allocated interrupt numbers must be a power-of-2,
and must be naturally aligned. I don't /think/ that's a requirement for
the virtual numbers, but it's probably best that we do it anyway.

So this API needs to specify that it will give you back a power-of-2
block that is naturally aligned - otherwise you can't use it for MSI.

rtas_call will return the numbers of hardware interrupt, and it should 
be power-of-2,
as this I think do not need to specify

quoted

+ * This routine is used for allocating and mapping a range of hardware
+ * irqs to virtual IRQs where the virtual irq numbers are not at pre-defined
+ * locations.

This comment doesn't make sense to me.

quoted

+ *
+ * Greater than 0 is returned upon success, while any failure to establish a
+ * static mapping is treated as an error.
+ */
+int irq_create_mapping_many(struct irq_domain *domain,
+		irq_hw_number_t hwirq_base, int count)
+{
+	int ret, irq_base;
+	int virq, i;
+
+	pr_debug("irq_create_mapping(0x%p, 0x%lx)\n", domain, hwirq_base);

I'd like to see this whole function rewritten to reduce the duplication
vs irq_create_mapping(). I don't see any reason why this can't be the
core routine, and irq_create_mapping() becomes a caller of it, passing a
count of 1 ?

It's good suggestion.

quoted

+	/* Look for default domain if nececssary */
+	if (!domain)
+		domain = irq_default_domain;
+	if (!domain) {
+		pr_warn("irq_create_mapping called for NULL domain, hwirq=%lx\n"
+			, hwirq_base);
+		WARN_ON(1);
+		return 0;
+	}
+	pr_debug("-> using domain @%p\n", domain);
+
+	/* For IRQ_DOMAIN_MAP_LEGACY, get the first virtual interrupt number */
+	if (domain->revmap_type == IRQ_DOMAIN_MAP_LEGACY)
+		return irq_domain_legacy_revmap(domain, hwirq_base);

The above doesn't work.

Why it doesn't work ?

quoted

+	/* Check if mapping already exists */
+	for (i = 0; i < count; i++) {
+		virq = irq_find_mapping(domain, hwirq_base+i);
+		if (virq) {
+			pr_debug("existing mapping on virq %d,"
+					" now dispose it first\n", virq);
+			irq_dispose_mapping(virq);

You might have just disposed of someone elses mapping, we shouldn't do
that. It should be an error to the caller.

It's a good question. If the interrupt used for someone elses, why I can 
apply it from the system?
So it may someone else forget to dispose mapping, and it never be used 
for others as I have got
the interrupt I think.

cheers